小编bal*_*alu的帖子

对于搜索功能，我使用的视图包含我需要搜索的所有表中的记录。该视图有近 2000 万条记录。针对这种观点的搜索花费了太多时间。

我应该在哪里寻找改善此视图的性能？

视图的粗略定义如下。它包括十三张桌子和大约三十个字段。

CREATE VIEW [dbo].[v_AllForSearch]
AS
SELECT 
  FT.firstField AS [firstField]
, FT.fld_primary AS [fld_primary]
, FT.fld_thirdField AS [thirdField]
, FT.fld_fourthField AS [fourthField]           
, ISNULL(ST.[fld_firstSearchField],'') AS [firstSearchField]
, ISNULL(TT.[fld_thirdSearch],'') AS thirdSearch
, ISNULL(TT.[fld_fourthSearch],'')AS fourthSearch
, ISNULL(TT.[fld_fifthSearch],'')AS fifthSearch
, ISNULL(FRT.[fld_sixthSearch],'') As [sixthSearch]
, ISNULL(FRT.[fld_seventhSearch],'') AS [seventhSearch]
, ISNULL(FRT.[fld_eightSearch],'')AS [eightSearch]
, ISNULL(FIT.[fld_nineSearch],'') AS [nineSearch]
, ISNULL(SIT.[fld_tenthSearch],'')AS [tenthSearch]
, ISNULL(SET.[fld_eleventhSearch],'') AS [eleventhSearch]
, ISNULL(ET.[twelthSearch],'')AS [twelthSearch]
, ISNULL(NT.[thirteenthSearch],'')AS [thirteenthSearch]
, ISNULL(NT.[fourteenSearch],'') AS [fourteenSearch]
, ISNULL(NT.[fifteenSearch],'') AS [fifteenSearch]
, ISNULL(NT.[sxteenSearch],'')  AS [sxteenSearch]
, …

我有一个包含以下文本的表格，我要搜索的关键字是“搜索”。所以我写了一个查询

SELECT [ID]
  ,[TextValue]
FROM
   [dbo].[SearchLike]
WHERE
   [TextValue] LIKE '%Search%'

Q.1如何修改查询，以便只返回文本中包含“搜索”的记录，而不是使用“LSearch”。即根据图像前三个记录只返回。？

我有类型为列的表NTEXT。并且由于某些特殊原因，客户端希望将列类型迁移到NVARCHAR(MAX).

这样做时，我应该注意哪些潜在威胁？

限制是否有数据丢失的可能性NVARCHAR(MAX)？